[GRASSLIST:2775] Re: general question (fwd)

David Irving dirving at box.net.au
Sat Dec 8 17:09:38 EST 2001

The remark by Dr Simpson is not strictly true. The reason that most
computers these days (and for about the last 30 years) are multitasking
is because you _can_ run multiple sessions without significant delays in
each process (within limits, of course). Most processes are, in turns,
CPU bound and I/O bound so, if a process has finished some calculation
and is then waiting for either a write to disk of the result or a read
from disk of more data, you can make significant gains by swapping it
out and swapping another process in, until the I/O has finished. I could
explain this in more detail without glossing over things (as could any
computing science undergraduate), but it's pretty tedious stuff to most


Gail Higginbottom wrote:
> I am forwarding this mail in answer to running multiple sessions.
> See below.
> best wishes,
> Gail.
> Gail Higginbottom,
> Centre for European Studies and General Linguistics,
> University of Adelaide,
> Adelaide, South Australia,
> Australia. 5005.
> and
> Department of Physics and Mathematical Physics
> ghigginb at physics.adelaide.edu.au
> http://www.physics.adelaide.edu.au/~ghigginb/
> (08) 8303:6440
> ---------- Forwarded message ----------
> Date: Fri, 7 Dec 2001 12:47:01 +1030 (CST)
> From: Ken Simpson <ksimpson at physics.adelaide.edu.au>
> To: Gail Higginbottom <ghigginb at physics.adelaide.edu.au>
> Subject: Re: [GRASSLIST:2754] general question (fwd)
> Not much point running multiple sessions on the same machine, since
> they will all take CPU time from each other and you will still have to
> wait the same length of time for everything to finish.  Better to
> write a shell script which can be run on several different machines (I
> have examples of this).
> Dr. Ken Simpson                         Tel: +61-8-8303-5036
> High Energy Astrophysics Group          Fax: +61-8-8303-4380
> U of Adelaide, SA 5005, AUSTRALIA       ksimpson at physics.adelaide.edu.au
> ************************************************************************
> > Just a general question is all I have...is it possible to modify a file
> > somewhere to be able to get multiple sessions of grass running on one
> > computer??  I lose a lot of time waiting for scripts that I have created
> > to run.
> > If not, is this a possible option for 5.1??  Thanks!!
> >
> > --
> >         LTJG Kevin Slover,NOAA   GIS Specialist/Meteorologist/Oceanographer
> >               Tropical Prediction Center/National Hurricane Center
> >                     11691 SW 17th Street Miami FL 33165
> >                  Work: (305) 229-4456 Fax : (305) 553-1264
> >

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